Metal ions have long been shown to be necessary for sugar binding activity of concanavalin A and certain other lectins. These lectins are of great interest because they are used extensively as cell surface probes. In addition, some, such as concanavalin A, will stimulate lymphocytes to undergo mitogenesis. A molecular characterization of carbohydrate binding and metal ion activation will aid researchers in their use of these probes and help to explain the way in which they influence cellular events. We are using several techniques to study both concanavalin A and a lectin from the lima bean. Nuclear magnetic resonance spectroscopy is being used to study how the carbohydrate binds to the protein. Electron spin resonance and fluorescence spectroscopy (along with several more standard techniques) are being used to study metal ion activation of the carbohydrate binding. BIBLIOGRAPHIC REFERENCES: Calcium Influence on Manganese Binding to Concanavalin A, J. A. Magnuson and G. M. Alter, Fed. Proc., 35, 1263abs (1976).